Due to the inherent speed of sound in tissue and the time required to perform the necessary signal processing, the rate at which ultrasound images can be produced may be relatively slow, e.g., on the order of 10 frames per second. At this rate, a physician or sonographer is generally able to detect a noticeable flicker on a monitor as the images are displayed. This flicker detracts from the ability of the physician or sonographer to interpret the ultrasound images.
One prior technique of eliminating flicker from a series of ultrasound images is to perform frame interpolation whereby at least two sequential ultrasound images are created and stored in a memory. A number of interpolated or synthesized images are then created by combining data from the stored images. All the images including the actual and interpolated images are then shown to the user beginning at a rate at which flicker is undetectable. As the interpolated images are being displayed, the next ultrasound image is being created and stored in memory for use in creating another set of interpolated images and the process continues.
While the technique method of producing interpolated images does reduce image flicker, the result is a series of images whereby objects in the image appear to blur from one image to another. This is particularly true when an object or speckle pattern in an image changes position between images. Using this method, an object will appear to fade out from a first position and fade into a second position with no indication of a path traveled by the object to its final position. Therefore, there is a need for a method of producing ultrasound images that increases the apparent frame rate without creating blurred images and while simultaneously illustrating the movement of an object within an image.